The nature of Cu–C bond and copper oxidation state in chloroorganocuprates [CuCl_nCH₃]²⁻ⁿ

Abstract

The adducts of copper(II) chloride complexes with organic radicals may be intermediates in reactions of halohydrocarbons proceeding via radical mechanism and in catalyzed by chlorocuprates. In this paper, the structure and reactivity of chloroorganocuprates with general formula [CuCl n CH 3 ] 2−n (n = 0–4) were studied at density functional theory (DFT) level of theory. The comparison of geometric and electronic structures of chloroorganocuprates and corresponding copper(II) chloride complexes with the same number of chlorine atoms indicates the higher Cu oxidation state in [CuCl n CH 3 ] 2−n . The Natural Bonding Orbital analysis confirms the formation of covalent σ‐Cu–C bond in these complexes. The analysis of the PES of the system CuCl 4 2− –CH 3 • indentifies two local minima, corresponding to CuCH 3 Cl 4 2− and weak complex CuCl 3 2− ···CH 3 Cl, as well as transition state between them. The calculations evidence the spontaneous character of copper ion reduction with formation of halohydrocarbon by chlorine atom detachment from CuCl 4 2− with high energetic effect. Copyright © 2013 John Wiley & Sons, Ltd.